Although advances have been made in the understanding of etiologies of thrombotic disorders and thrombotic microangiopathies, the majority of afflicted patients do not have an identified mutation or predisposing risk factor. To better understand the molecular defects in thrombotic disorders and thrombotic microangiopathies, future work will have to identify mutations that exist in DNA and the specific activity of plasma proteins. Therefore, a core will be established to facilitate the collection of blood samples from eligible patients. This core will function to archive plasma and DNA samples from patients with thrombotic microangiopathies and other thrombotic disorders and will operate within the parameters of the existing and successful Translational Pathology and Molecular Phenotyping Core (TPMPC) at Washington University. The core will also establish and maintain a database that will capture relevant epidemiological, disease-related, prognostic, therapy, and outcomes data with de-identified linkage to corresponding banked plasma and DNA samples. The Thrombotic Disorder Banking Core will be responsible for identifying patients eligible for sample collection, obtaining informed consent from eligible participants, collecting blood and using the blood samples to obtain plasma and DNA isolated from white blood cells within the blood sample. Inclusion criteria for the collection of samples will include the diagnosis of a thrombotic microangiopathy such as thrombotic thrombocytopenic purpura, atypical hemolytic uremic syndrome, and HELLP syndrome associated with pregnancy for the studies in Project 1 and 2. Blood samples will be taken at diagnosis and again during outpatient follow-up. The core is essential to individual research projects because it will provide DNA for whole exome sequencing of complement pathway proteins, coagulation pathway proteins, and other candidate genes likely to be involved in the pathogenesis of thrombotic microangiopathies. Specifically, this core will be instrumental to the aims of Projects 1 and 2 in this application. Archived plasma and serum samples will be critical to the success of Project 1 (Pathophysiology and Treatment of Thrombotic Microangiopathy (Sadler)) that seeks to understand the pathophysiology and treatment of thrombotic microangiopathies. Plasma from control patients and those with thrombotic thrombocytopenic purpura (TTP) will be used to develop rapid and sensitive assays of ADAMTS13 activity and inhibitors of ADAMTS13. Furthermore, plasma and DNA samples will be used for clinical phenotyping and for the evaluation of specific treatments. Samples will also be used to characterize defects associated with previously unrecognized mechanisms of thrombotic microangiopathy. Project 2 (Genetic Predisposition to the Thrombomicroangiopathies (Atkinson)) will identify mutations in other complement and coagulation proteins in atypical hemolytic uremic syndrome (aHUS), a type of thrombotic microangiopathy. To date, mutations in five complement proteins and in a regulator of hemostasis have been identified in patients with aHUS. Because only 70% of patients have identified mutations, further work is needed to characterize the defect in the other 30% of aHUS patients. There is also data to suggest that mutations in these proteins may also be present in those with antiphospholipid syndrome and the HELLP syndrome of pregnancy. We will utilize the services of the existing Translational Pathology and Molecular Phenotyping Core (TPMPC) within the Institute of Clinical and Translational Sciences headed by Dr. Mark Watson at Washington University. The core will be responsible for cryopreservation of plasma from the blood samples, for isolation of white blood cells, for purification of DNA from the white blood cells and for data management. Blood samples will be assigned a unique, randomly-generated six digit patient identification number at the time of consent. A label with the six digit number will be used on the blood samples and on a paper master list that contains the patients name, medical record number, date of birth and date of consent. The master list will be kept in a locked safe. The key to this safe will be held by the research coordinator, the core director, and the principal investigators. The blood samples will be hand carried to the tissue procurement lab within 2 hours. In addition, duplicate samples will be processed and stored within the hematology division to insure sample integrity. The Translational Pathology and Molecular Phenotyping Core has been used successfully by many groups including an acute leukemia group and a breast cancer group at Washington University for the prospective collection and processing of human blood and tissue specimens associated with clinical trials.